There are several medical conditions which can benefit from implantation into a patient of a filler material, an embolization or other device, whether temporary or permanent. Examples include the closure of blood vessels or other lumens. Another example for which such procedures can be particularly useful is in the treatment of aneurysms, where a part of a vessel wall weakens and then expands outwardly to create an enlarged zone of the vessel, often having the form of a sac. This vessel expansion occurs as a result of blood pressure and tends to continue due to further and progressive weakening of the vessel wall. If left untreated, persistent pressure from the blood flow on the weakened wall tissue can lead to eventual rupture of the vessel and consequential haemorrhaging. Treatments for aneurysms have therefore focused on reducing the pressure on the weakened vessel wall, for instance by diverting blood flow or by isolating the weakened vessel wall, for instance by means of a stent graft. Another treatment method involves filling the aneurysm sac with a filler material which stops the flow of blood into the sac and therefore stops or substantially reduces the pressure on the weakened walls. The filler may be an embolization coil, which will cause blood therearound to clot and thus close the sac and provide a protective barrier to prevent blood flowing into the sac and thereby to prevent rupture of the weakened section of the vessel. In other instances, the aneurysm sac may be filled with a biocompatible material, such as a hydrogel or a polysaccharide fibre, which may be of a biodegradable nature. A biodegradable filler performs the same function as an embolization coil, that is to fill the aneurysm sac and provide pressure protection to the weakened vessel walls, with the additional advantage of allowing remodeling of the vessel wall over time. Moreover, biodegradation of the filler will ensure that no foreign matter remains in the patient's vessel after conclusion of the treatment.
Such fillers and coils can also be used to close off a vessel or other lumen in a patient.
The process of introducing such a filler or coil into a patient can take time, particularly given that this is often carried out remotely from the aneurysm by an endoluminal procedure. There is also the risk that the filler material can escape from the aneurysm sac, not only during the filling procedure but also after. It has been postulated that this can be avoided by implantation of a stent or stent graft across the aneurysm, though this entails leaving in the patient a foreign object. It has also been postulated to use a balloon to close off the aneurysm while it is being filled but this entails the closure of the vessel, which necessarily reduces the amount of time the balloon can remain in the vessel.
Examples of prior art devices and methods can, for instance, be found in US2012/0316632, U.S. Pat. Nos. 6,780,196, 8,597,320, 7,875,044, US2012/091171, U.S. Pat. Nos. 6,569,190, 6,312,421, US2006/0147483, U.S. Pat. Nod. 6,589,199, 6,440,098, WO2011/003147, US2011/319917, WO2009/124288, US2005/119684, US2011/046716, and WO2006/044632.
There are other medical applications in which a wire member can be employed having particular characteristics in response to applied forces. Medical devices falling into this category include stents, filters and devices for retrieving blood clots, especially from the brain. A device for implantation inside a patent is disclosed in WO-96/41589 in which rhombus-shaped wire cells have intertwined regions which extend in the circumferential direction of a tubular element.